A fuel pump control system or device is known in the art, according to which fuel is supplied by a fuel pump from a fuel tank of an automotive vehicle to an internal combustion engine.
In one of the fuel pump control systems, electric power is supplied from a vehicle battery to the fuel pump control system via a relay device so that the fuel pump control system is operated. An on-off operation of the relay device is controlled by an engine control unit (an engine ECU). When an operation of the internal combustion engine (an engine operation) is going to be stopped, the relay device is turned off by a control signal from the engine ECU to stop an operation of the fuel pump (a pump operation).
In an automotive vehicle having an idling-stop function, the relay device is turned off during an engine stopped period, in which the engine operation is temporarily stopped as an idling-stop operation. In a hybrid vehicle having an internal combustion engine and an electric motor as a vehicle driving device, the relay device is turned off in a vehicle running period of an EV running mode. As above, the relay device is turned off to stop the pump operation in a condition that an ignition switch is turned on, when the engine operation is temporarily stopped during a vehicle running operation. As a result, an on-off operation of the relay device is repeatedly done.
The fuel pump may run idle when fuel becomes insufficient. When the relay device is turned on during the temporal engine stopped period in the vehicle running operation, the fuel pump may run idle in a case of shortage of the fuel. Then, the fuel pump control system may erroneously determine that an abnormal condition is caused by a disconnection in a power supply path, through which the electric power is supplied from the vehicle battery to the fuel pump via the relay device, in spite that the fuel pump is running idle due to the shortage of the fuel.